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erc-c/include/mos6502.enums.h
2018-01-05 14:18:39 -06:00

118 lines
3.5 KiB
C

/*
* mos6502.enums.h
* Enums and other symbols for use with the mos 6502
*
* We have separated the definitions of address mode types, instruction
* types, etc. into their own file so that we can include it in our main
* source file, as well as from our unit test suite, without necessarily
* adding them to the global namespace throughout the application.
*/
#ifndef _MOS6502_ENUMS_H_
#define _MOS6502_ENUMS_H_
/*
* This defines all of the flags that are possible within the status (P)
* register. Note that there is intentionally _no_ definition for the
* 6th bit.
*/
enum status_flags {
MOS_CARRY = 1,
MOS_ZERO = 2,
MOS_INTERRUPT = 4,
MOS_DECIMAL = 8,
MOS_BREAK = 16,
MOS_OVERFLOW = 64,
MOS_NEGATIVE = 128,
};
/*
* Here we define the various address modes that are possible. These do
* not map to any significant numbers that are documented for the 6502
* processor; the position of these symbols don't really matter, and are
* generally (except for `NOA`, no address mode) in alphabetical order.
*/
enum addr_mode {
NOA, // no address mode
ACC, // accumulator
ABS, // absolute
ABX, // absolute x-index
ABY, // absolute y-index
IMM, // immediate
IMP, // implied
IND, // indirect
IDX, // x-index indirect
IDY, // indirect y-index
REL, // relative
ZPG, // zero page
ZPX, // zero page x-index
ZPY, // zero page y-index
};
/*
* These define the various instructions as enum symbols; again, like
* for address modes, the values of these enums are not actually
* significant to the 6502 processor, and are only useful to we, the
* programmers.
*/
enum instruction {
ADC, // ADd with Carry
AND, // bitwise AND
ASL, // Arithmetic Shift Left
BCC, // Branch on Carry Clear
BCS, // Branch on Carry Set
BEQ, // Branch on EQual to zero
BIT, // BIT test
BMI, // Branch on MInus
BNE, // Branch on Not Equal to zero
BPL, // Branch on PLus
BRK, // BReaK (interrupt)
BVC, // Branch on oVerflow Clear
BVS, // Branch on oVerflow Set
CLC, // CLear Carry
CLD, // CLear Decimal
CLI, // CLear Interrupt disable
CLV, // CLear oVerflow
CMP, // CoMPare
CPX, // ComPare with X register
CPY, // ComPare with Y register
DEC, // DECrement
DEX, // DEcrement X
DEY, // DEcrement Y
EOR, // Exclusive OR
INC, // INCrement
INX, // INcrement X
INY, // INcrement Y
JMP, // JuMP
JSR, // Jump to SubRoutine
LDA, // LoaD Accumulator
LDX, // LoaD X
LDY, // LoaD Y
LSR, // Logical Shift Right
NOP, // NO oPeration
ORA, // OR with Accumulator
PHA, // PusH Accumulator
PHP, // PusH Predicate register
PLA, // PulL Accumulator
PLP, // PulL Predicate register
ROL, // ROtate Left
ROR, // ROtate Right
RTI, // ReTurn from Interrupt
RTS, // ReTurn from Subroutine
SBC, // SuBtract with Carry
SEC, // SEt Carry
SED, // SEt Decimal
SEI, // SEt Interrupt disable
STA, // STore Accumulator
STX, // STore X
STY, // STore Y
TAX, // Transfer Accumulator to X
TAY, // Transfer Accumulator to Y
TSX, // Transfer Stack register to X
TXA, // Transfer X to Accumulator
TXS, // Transfer X to Stack register
TYA, // Transfer Y to Accumulator
};
#endif